Landing gear construction



June 30, 1959 R. c. scoT-r- ETAL LANDING GEAR CONSTRUCTION Filed Aug. 1'?. 1955 2 Sheets-Sheet l June 30, 1959 R. c. SCOTT ET AL T 2,892,626

LANDING GEAR CONSTRUCTION Filed Aug. 17, 1955 2 Sheets-Sheet 2 INVENTORS ROBERT C. SCOTT BY WALTER H. HOGAN United States Patent LANDING GEAR CONSTRUCTION Application August 17, 1955, Serial No. 528,991

15 Claims. (Cl. 267-64) This invention relates generally to a landing gear and more particularly to a landing gear which may be compressed so that it may -be stored in a small space in the aircraft upon retraction.

It is an important object of this invention to provide a landing gear incorporating an oleo mechanism which may be compressed to reduce the space necessary for storage of the gear upon retracton.

lt is another important object of this invention to provide a landing gear wherein the pressurized uid of the oleo is utilized to assist in compressing the gear so that it may be stored in a small area upon reaction.

It is still another object of this invention to provide a landing gear utilizing differential opposed areas which permit easy compression of the oleo mechanism.

`It is still a further object of this invention to provide a landing gear having an area which may be subjected to thefiuid `under pressure in the oleo mechanism which area assists in compressing the landing gear.

Further objects and advantages will appear from the following description and drawings, wherein:

Figure 1 is a side elevation in longitudinal section of a landing gear according to this invention shown in the extended position;

Figure 2 is a view similar to Figure 1 showing the position of the elements when the landing gear is fully compressed by the weight of the aircraft;

Figure 3 is a longitudinal section showing the position of the elements when the landing gear is compressed for retraction; and,

Figure 4 is a side elevation in longitudinal section of a modified form of this invention. i Y

In many modern aircraft, it is highly desirable to be able to compress the landing gear either during theretraction thereof or prior to the retraction so that it may be stored in a small area within the air frame. This is particularly important in the modern military aircraft since space is at a premium due to the vast amount of equipment which must be carried by the ship. However, reduction of the size of the landing gear storage space is desirable in all aircraft installations since it simplifies the structure of the air frame itself and makes it possible to increase the strength of the components without increasing the weight.

For a clear understanding of the invention, reference should be made to Figures l to 3 wherein one preferred landing gear according to this invention is shown. The landing gear is provided with an upper telescoping member 10 closed at its upper end by a cap member 11v on which is formed a mounting trunnion 12 adapted to be fixed to an aircraft. A lower telescoping member, 13

ber 10 and is capable of axial motion relative thereto. Torque arms 14 are pivotally connected to the upper telescoping member 10 and lower telescoping member 13 and prevent relative rotational motion while permitting relative axial motion between the members. engaging wheel 16 is journaled at the lower end of the v oleo chamber 32.

y 2,892,626 Patented June 30, 1959 "lee lower telescoping member 13. The lower telescoping member 13-is formed with an upper bearing portion 17 which engages the inner wall of the upper telescoping member 10 anda gland nut 18 is securely retained against a shoulder 19 formed in the upper telescoping member 10 by a flanged lock nut 21. Seals 22 prevent leakage of fluid between the gland nut 18 and the two telescoping members 10 and 13.

An oleo structure is provided within the strut to support the weight of the aircraft when it is on the ground and to absorb the impact shock during landings. The main oleo cavity is defined within the strut by an upper bulkhead 23 secured against the shoulder 24 formed in the -upper telescoping member 10 by a snap ring 26 and an integral lower bulkhead 27 formed across the lower telescoping member 13. The upper bulkhead 23 is formed with an axially extending plunger tube 28 which extends into the upper end of the lower telescoping member 13. An orifice plate 29 mounted on the plunger tube 28 divides the main oleo cavity into a lower oleo chamber 31 below the orifice plate and the upper oleo chamber 32 above the orifice plate which chambers are in fluid communication through a central orifice 33 formed in the'orifice plate 29. lt should be understood that the upper yoleo chamber 32 includes the area between the upper telescoping member 10 and the plunger Vtube 28 as well as the area within the plunger tube and that fluid communication is provided between these areas by a plurality of ports 34 formed in the plunger tube.

When the landing gear or strut is in the fully extended position shown in Figure 1, the lower oleo chamber 31 is filled with a liquid as is the lower portion of the upper The remaining portions of the upper oleochamber 32 are charged with air under pressure which pressure is of course transmitted to the liquid in the two chambers 31 and 32. The bearing portion 17 is formed with a plurality of small orifices 36 which provide fluid communication between the upper charnber 32 and a rebound chamber 37 around the lower telescoping member 13. The rebound chamber 37 is also lled with liquid and functions in the usual manner to control rebounds after landing. Those skilled in the art will recognize that the fluid under pressure within the oleo chambers-31 and 32 produce a reaction force on the lower telescoping member 13 which is a function of the pressure of the fluid times the area within the gland nut 18 and this force resiliently urges the lower 'telescoping member 13 downward relative tothe upper telescoping member 10.

Above the upper bulkhead 23 is a compressing mechanism utilized to assist in the compression of the strut when it is desired to retract it into the aircraft. Positioned within the cavity above the upper bulkhead 23 and the cap member 11 is a slidable piston 38 which divides the cavity into a frst chamber 39 and a second chamber 41. The first chamber 39 is connected to the upper oleo chamber 32 through a control valve 42. The control valve is a simple on/off valve which may be opened to provide fluid communication between the chambers 39 and 32 or closed to isolate the two chambers. An operating valve 43 connects the second chamber 41 to a source of fluid under pressure (not shown) i by a pressure line 44 and to a reservoir return through a y"A projects intothe lower end of the upper telescopmg mernv 70 A ground second pressure line 46.

Securely mounted on the lower bulkhead 27 is a metering pin 47 which projects through the orifice 33, the upper bulkhead 23 and the piston 38. The upper portion of the metering pin 48 which projects through the upper bulkhead 23 and piston 38 is formed with a uniform cross section and seals 49 and 51 mounted on the upper bulkhead 23 and piston 38 respectively prevent fluid leakage along the metering pin but permit the metering pin tolmove"'axially. The lower portions'iofy themrnetring pin 47 which are within the oritce 33 during the operation of the strut are contoured to provide the desired resistance to ow throughI the orifice so that a proper "-lfoad'stroke 'curve will -be developedto absorbithe impact "of l1'1`d1` 11g.y "Anutfastener' 52"is Vthrreadedonto .theznp- "peifendof ther-metering"v pin 47 above {the'piston 38and pon"V 4engagement therebetween-limits lrelative axial inovenien't in one direction. `The variousproportions -are 10 To extend the gear after it has been compressed for varranged `so that when the landing gear is in the extended `"-po'sition"shown in Figure l' and'the'piston is adjacent to the upper bulkhead 23thefnut` SZVengages the upper "side v`of thep'iston'SS. This -structurefpermits axial-"mo- "e pt Whenit-he-nutSZfenga'ges the'pis'ton'at'which time. the ymetering pin 47 `and -piston'38 'are'restfrained against relaftive afiial motion in" one direction.

'llrropera'tiom "assuming thelandinglgear' isV inthe fully l" 'ezctendred position; Athe"valve42y y.is 'closed isolating vthe i "tirst' chamberf'39 andthe-upper oleoehamber 32. AtA this "time4 the 'pressure lwi-tliinlthe rst chamberv 39 is equal t Aev pressure within the upper oleo chamber' 32and fthefpl'stn- 38 is"adjac'ent=t0the bulkh`ead23. When A-ai "latidingg the lower telescopingimember `13` moves vupfwa'rdlvrelative )to the Auppertelescopir'ig member 10 eau's'inga compression ofthe gaswithinf-.the'rupper oleo *chamber 32 until the reaction forcezon the'lowcr telescop- *ling member -13fequals the Vload carriedr-by the strut. .30

-relativefto the uppertelescoping,mcmberflt) through the fupper bulkheadS and piston/38. lhepiston V38 will not'move'upwardly/.relative to the-upper telesoping 'memberflt) sincect'ne hrstcharnber-Q isgilsolated vfrom l'ftheupper'roleo'chamber'32ibysthe .valve 412e. In some `cases :it mayv Abe :desirable `to thread heimetering pin .147

`finto the lpiston 38 `so that v.they 5are axially ttigedgreluative ifto=;each other. `If Ethisis done the piston n38 lwill be "pushedup fbythemereriegfpin duriugtheleudingfcausing '.avacuum in -gthefirst chamber 39. In such xeases the :second chamber .lgrnay beavented that the pressure ;;therein-;wi 1l not build iup thereby limiting tlvieiforcen `on Yitheripiston `3.8 'whichinusl be :Carried by the meteringpim .:It should-be noted that this force Y,ass ists.,.in .supporting the aircraft. Y Y l `s' l dfieasily- ,lnrthefembcclment Shen. e

ay'be 20 Ysufficient to tovercome the dife communication with a source *of huid" "'under "pressure through .the pressureline A44. The Huid withiny vthine-,second 15 chamber 41, ofcourse, produces Yareaetion force on the piston 38 in downward directioniand tends to neutralize the pressure within the rst chamber 39. Therefore, as soon as the pressure within the second chamber builds up to e value large-.enough to produce azreaetionfhorce lrbtweenfihsuweid `than' theLeiectve4 area'of the 'lower itelesveoping ,1327, therefore, when vthe control valve 4 V- isfopened fue siruffwiu .assumereiexfendedipositw because the .50 between theA glandnutijleS" and the'b'earin'g `portion 17',

``Theactuatingfchamber'53',is adapted to b'evconneoted jto a source-of Huid-"under pressure throughlano'perating valv'e'56': -`Prior to the-landing of-- the' i 'aireraftwhen-the *strut is fin' jthejf-e`ii'ten-delposition; the Ycontrol AvalveillZ' @isL closed "and-the upper oleolchaniberZf is isolatedfrom i the'-"chralrnber'i39'; Ltl'le'refore,thepistor 38'- Will-lnot move --'pwa'rdlyv witli-thelower =telescopingmember13Lwhen a landing occurs. 1n this embodiment.compressio-n-ofrthe Vlstiu'tlfor=r^etra`ctio`n isaccompli'shed by opening thelcontrol f ating f 'chamber' T53 through the f. operating '.yalve" n.56. The reactionlzforcepon ithepiston38- is less Athan the .reflotionlforceoflithe fluiduvithin'athe oha'mberr32' so it ff is-'neeessary to' provide an'ladditional. upward? force-to the fluid initier! pressur'ewithinlthe,'aetuatiugzchamberrS' `faeting onthbearinglportion-1175*'SHereagain the force "jn'ec'essaryl- VAto operate? theqI strut lisJ only ithat vL force 'I' nec,essarv4 to* overcome theditlt'rential between 'fthevforce ose'skille I ini'the art vvill recognize that a landing gear` incorporating thi'sf invention 'ma'ybeffully'rcompressed Withoutproviding elaborate equipment to-developilar'ge compressionforces and'that thefstrut: tendsv t'o' operate itself; therefore, a: simple mechanisml which is light in vveightrnay 'be utilized- Without substantially increasing the manufacturingcostfor'rnaintenance problems.-

Although'preferrdenibodiments ofI 'this invention are illustrated',"itf will' be} real iz 'ed that various modifications o 'fjth structural detailsv maybe'made without departing frornj"the mode 'ofi-op ation"and "the `essen'ce-"of,l the pf'nsofar as'tliey-are-claimed `claims, structural details 1"' may be' edfwid'ely lthou't modifying' the Amode of operation. Accodingly ,the app`e de aims? and not the l-`afor e sz 1id weidaimf 1.' A` la1;1ding gear comprising rst and second cooperating"`teles'cfopi ng j rnenib'e'rs, 'rne'aris inl-'each ofjs'aid members coop'elatin'gto definea pressure' duid iilledcavityfthe volurneoil which is chang'd b'yirelative aXialf motion beaidmeinbers', a i 1 actuatedpiston movable rela- Y Y means"conriciting said-cavity and one vside o said "p istonf'i'r.4 maintaining the 'fluid pressure on said @ne Sidefgf s ard pistonequal to thel fluid pressure in said vity'jan'd 'operable to isolate said piston and said cavty'f,' Sajdpressu'r'efnuid producing 'a first reaction .force on'said second member urging it' axially-away from said'rstmember and a 'secondv reaction force on s'a'id `piston tending jto' move itirela't'iv'e to saidmembeIS, and' meansI connecting, said" pistonf and second -rnernber whereby 'said' second 're'ac'tion1forceopposes saidl rst re-i reaction force tending t'of move it' relative to'said' members, 'and means connecting 'said piston and second member adapted to transmitsaid secondreaction force to said secondmemb'er Whereby'saidsecfondreaction force opposes. said rst reactiori'fice 'andj moves saidI second member aXially toward said ii'rst member when said valve 'means connects saidfcav'ilty vand piston.'

3.. .landing fgear 'comprising' 'frst and second kcooperating telescopingrnembersa'bulkhead in each of said membersooperating -to gdeiine" a' pressure fluid lilled cavitythe .volume of which is', changed by relative axial motion between said members, 'a' fluid actuated piston movable Yrelativeto said members, 'valvem'e'ans connectingsa'idcavity and oneside of vsaid piston for maintainingthe` uid pressure on saido'rie side of said piston equal-to'theeuid. pressure, in said -cavity and operable to isolate said pistonf and said cavity, said 'uid under pressure producing a first" reaction force on said :second memberturging it .axially awayfror's'aid 'iirst member and asecond reactionl'fo'rcen saidpisto'n larger than' saidr rst vreaction force tendingto move it relative to said ber adapted' to transmitsaid second IeactiQnorCeto-Sid second' member'vvherebyfsaidisecond reaction` force 'opposeswsaidiirs't reaction vforce ar1`d "frr1o'v es said-second memberaxially to'vvani` s'aidflirs't member Whengsaid valve means connects Asaid cai'fi'ty"4 andlpist'on," and-'meansfto assist -fsaid iirstreaction' force and move said second member awayfrom said iirst member-.f1 f

f v'4.' A' landing gear" comprising lirst and second cooperatingY telescoping-4 nner'nbes""c'zapabl'e` of'rela'tiveaxial motion,- a bulkheadfin :eachif said-1 'members' vcooperating to define a 'pressur'eflriid filledcav'ity 'thevolu'rne oftwhich is changed by relative airilinotionbetween' said members, a' fluid i actuatedA pistonfmovbl'e r'elativ'' 'to -said members,

' valve meansv connecting said cavity andfon's'ide 'o aid ondfni'emberurgiri piston for maintaining the 'fluidi pressure 'on saidcne'side ofY said' piston* 'equl'f to "the y"Huid 'pressure 'l in "saidff' cavity operable to isolate said piston and said cavity, said-'pressure' fluid v'prodcin'g'f a first' reaction-force ""on said l-secit aiiially aw'ayfrorn- 's'ai'dfiir'st" 'membr'and'fasecon eacti frc fon-"said'p stonsmall'er than said' iirstv` r'e'act'i forcetending-'ttiV move ity relative tofsaid-rnemb'e' connecting' means' bet'v'veen s'ad pistonandf 'second inemb'er'*limiting'movement V'cf' said piston relative to' 'second'm'cmbe -Wherby saidA 'second' reaction force opposes said'fr'stir'ectionf 'force' andl tends to rnove said""secondY member' XiaIlytovt/a'rdsid 'first member when said valve-x "eans connects said'cavity-and aid is'tc'nl infmoving'fs'aid'sec- 1A5; landing'gear corr'ipris'ing'firstL and second cooperatng" telescopingmf'nlerrbers' 'ec'pabl'e 'of' relative' axial r'noti'oriA between afully' "extended position fand* la flly compressed position, "a bllrhead in eachl of'said members cooperating to ide'ii'ne'a' fpif sure-uidlled cavity'the volumeof'vvhiclis ohanged'fbyrelatve axial` motion betion sa'idmernbers; apistnislidablef'in s'a'id'iirs't member on the side of said rst menibiblkhedf remote from sid 'c avit'yp said `piston and r'stme'mber' bulkhead cooperating'to define auid 'chamber thei'volurnejofwhi" changed by -aiialy motion of said piston,y valvemea'ns nesting said chamber and cavity adapted 'toisolatethem and operablefto povide uid communication-therebetiveen,v connecting rne'ansI between' saidl 'secondV member faces limiting axialmotionjbif'said `Pto'n'"'relative to said second member inf af'directionff'away from said second member upon'v such engagement, said" connecting means being, proportioned to: cause' engagement between' 4' said stop surfaces` when" said; members arel in'said rfully e'X- l tion betweenaful'lyfexten tended position"and"said:v pistonis- 'substantially adjacent to saidgrstmemb'erbullde i 'i "i" 6. A 'landing'gerrcompnsingxiirst and` second cooperating telescoping members' 'capable"of relative "axial mopcsttionfanda fullycompressed position, 'a,jbi'llkhe'adY eacliforsaidfmemb'ers cooperatingtodeiine'a pressure luidlled cavity thevo'lu'me offwhichi is' changed byV relativef' aXia l 'motion between said rnernbers,r a` 'pist'on'slidable`in said 'first member; on

" the side of said firstmember bulkhead remote from said changed 'byn airialTmotijon cavity, said,p 1' s t on ndj'rstmer'nbr bulkhead cooperating'todefine' aji'ndfchamber the"vol 1'1me of which Yis said pistont valve means connectingsaid chamber` and vcavity adapted-tofisolatetliefm and operable'to provitieuidlcommunication therebetween," Connecting means between' Said Second'member andsaid piston providing mutually engageable lstop' surfaces limiting axialmotion of said' piston relative to said second memberin only adirection aw'ayriirom vsaid second v member'upon such"en'gag rnent, and meansV adaptedA to urge said ber.'

7. A landing gear comp r ising f r s t andsecond cooperatingtelescop'ing members cpablelof relative aiiialr'r'ropiston in adirectionftovva dsaidfs'econdpmemj tion between afully extended position and a fully compressed position, a bulkhead 'in each of said members cooperating to define a pressure fluid filled cavity the volume of which is changed by relative axial motion be- ,v tween said members, a piston slidable in said first mem- A b evr en the side ofpsaid first member bulkhead remote from said cavitypsaid piston and first member bulkhead cooperating to define a fluid chamber the volume of which is changed by axial motion of said piston, valve means connecting said chamber and cavity adapted to isolate them and operable to provide fluid communication there- 4 between, connecting means between said second memd opposite said chamber to urge it toward said second member.

8. A landing gear comprising first and second cooperating telescoping members capable of relative axial motion, a bulkhead in each of said members cooperating to define a pressure fluid filled cavity the volume of which is changed byrelativeaxial motion between said members, said pressure fluid producing a reaction force on the effective area of said second member urging it axially away from said first member, a piston slidable in said first member on the side of said first member bulkhead remote from said cavity, said piston and first member bulkhead cooperating to define a fluid chamber the volume of which is changed by axial motion of said piston, valvev means connecting said chamber and cavity adapted to -isolate them and operable to provide fluid communication therebetween, the effective area of said piston exposed to fluid in said chamber being different than the effective areadof said second member, connecting means between said second Amember and said piston limiting axial motion of said piston relative to said second member upon such engagement.

9. A landing gear comprising first and second cooperk'ating telescoping membersY capable of relative axial motion, a bulkhead in each of said members cooperating to define a pressure fluid filled cavity the volume of which is changed by relative axial motion between said members, said pressure fluid producing `a reaction force on the effective area of said second member urging it axially away from said first member, -a piston slidable in said first member on the side of said first member bulkhead remote from said cavity, said piston and first member bulkhead cooperating to define a fluid chamber the volume of which is changed by axial motion of said piston, valve means connecting said chamber and cavity adapted to isolate them and operable to provide fluid communication therebetween, the effective area of said piston exp'osed to fluid in said chamber being different than the effective area of said second member, connecting means between said second member and said piston providing mutually engageable stop surfaces limiting axial motion of said piston relative to said member upon such engagement, said connecting means being proportioned to cause engagement between said stop surfaces when said lmembers are in said fully extended position and said piston is substantially adjacent Itosaidlfirst member bulkhead.

l0. A landinggear comprisingfirst and second cooperating-telescoping members. capable of relative axial motion, a bulkhead in each of said members cooperating to define a pressure fluid filledcavity the volume of which is changed by relative axial motion between said members, said pressure fluid producing -a reaction force on the effective area of said second member urging it axially valve means connecting said chamber and cavity adapted to isolate them and operable to provide fluid communication therebetween, the effective area of said piston e'xposed to fluid in said chamber being larger than the effe'ctive area of said second member, connecting means b etween said second member and said piston limiting axial motion of said piston relative to said second member upon -such engagement whereby said piston overcomes second member reaction force and moves said second member toward said first member when said valve means connects said chamber and cavity.

1l. A landing gear comprising first and second cooperating telescoping members, means on each of said members co-operating to define a pressure fluid filled cavity the volume of which is changed by relative motion between said members, a fluid actuated piston movable relative to said first member, valved means connecting said cavity and one side of said piston maintaining the fluid pressure on said one side of said piston equal -to the fluid pressure in said cavity and operable to isolate said piston and said'cavity, said pressure fluid producing a first reaction force on said second member urging it axially away from said first member and a second reaction force on said piston tending to move it relative .to said first member, and means connecting said piston and second member transmitting said second reaction force to said second member in opposition to said first reaction force, the difference between said reaction forces being less than said first reaction force.

12. A landing gear comprising a pair of telescoping members cooperating to define a cavity filled with pressure fluid the volume of which is reduced by telescoping movement of said members toward each other, au element extending through said cavity mounted on one of said members provided with a piston engaging the other of said members, said piston defining part of a chamber isolated from said cavity the volume of which is increased by said telescoping movement, valved means cnnecting said cavity and chamber normally maintains the pressure in said chamberY equal to the pressure in 'said cavity and operable to isolate said chamber from said cavity, the pressure fluid in said cavity producing a 'reaction force urging said members apart and the pressure fluid in said chamber producing a reaction force urging said members toward each other.

13. A landing gear comprising a pair of telescoping members, a cavity filled with pressure fluid in said members, said cavity including a first surface on one of said away from said first member, a. piston slidable in said first member on the side of said first member bulkhead remote from said cavity, said piston and first member bulkhead cooperating to -define a fluid chamber the volume -of which is changed by axial motion of vsaid pistpn,

members acted upon by said pressure fluid producing a first reaction force urging said members axially apart, a second surface adapted to be exposed to said pressure fluid which produces Ia second reaction force thereon'in a direction opposite said first reaction force, said second surface being normally isolated from saidtcavity and connected to said one member, valved means operablefto provide fluid communication between said second surface and said cavity equalizing the pressure of the fluid acting on both of said surfaces. l

14. A landing gear comprising a pair of telescoping members capable of relative movement between extended and compressed positions, a cavity filled with pressure fluid in said members, said cavity including a first surface on one of said members acted upon by said pressure fluid producing a first reaction force urging said members toward said extended position, a second surface adapted to be exposed to lsaid pressure fluid which produce a second reaction force thereon in a direction opposite said first reaction force, said second surface being normally isolated from saidcavity and connected to said one member, valved means operable to provide fluid communication between said second surface and said cavity equalizing the pressure of the fluid acting on both of said surfaces,

l said second reaction force urging said members toward second surface adapted to be exposed to said pressure 5 fluid which produce -a second reaction force thereon in a direction opposite said first reaction force, said second surface being normally isolated from said cavity and connected to said one member, the effective area of said first surface being diterent from the elfective area of 10 2,679,827

said second surface, valved means operable to provide fluid communication between said second surface and said cavity equalizing the pressure of the ud acting on both of said surfaces.

References Cited in the le of this patent UNITED STATES PATENTS Levy May 29, 1951 Katz July 10, 1951 Perdue June 1, 1954 

